This application relates to a medical or dental handpiece with a clamping or chucking device.
A handpiece with such a chucking device is known, for example, from patent application US 2009/0220911 A1. The chucking device is designed to hold the tool at two different insertion depths, so that the length of that part of the tool that projects from the chucking device (and thus from the handpiece) can be altered. For this purpose, the chucking device has two independent sections offset from one another and arranged along the longitudinal axis: One elongate section located at the upper end of the chucking device, for transmission of torque to the tool and for the support and centering of the tool in the chucking device, and one radially spring-mounted section formed by spring shackles for the axial holding of the tool in the chucking device.
The disadvantage of this chucking device is that, particularly when the tool is in the position in which it projects further from the chucking device, only a very short end section of the shaft is held in the section for torque transmission, so that the tool is only insufficiently held and centered in the chucking device (see, for example, FIG. 11 of US 2009/0220911 A1). Thus particularly at high speeds there is a danger that the tool will not turn smoothly or will start to vibrate.
It would be advantageous to create a medical, particularly a dental, handpiece with a chucking device designed to hold the tool in two different insertion depths, wherein the tool, particularly in the position in which it projects further from the chucking device, is supported and centered better in the chucking device.